An electrode adopted in an electrochemical fuel cell comprises a catalyst layer and a gas diffusion layer. Two of the electrodes contact an electrolyte membrane on each side of the electrolyte membrane. The catalyst layer functions as an anode or a cathode on each surface of the electrolyte membrane. The gas diffusion layer, which diffuses and supplies gas to the catalyst layer, is deposited on the outer side of the catalyst layer.
The gas diffusion layer functions not only as diffusing a gas as mentioned above, but also as removing moisture which comes out on the surface of the catalyst layer, or etc. Accordingly, a good gas diffusion ability, a good electric conductivity, and a good water repellency are required for the gas diffusion layer.
In order to improve the electric conductivity of the gas diffusion layer, in usual case a carbon-based material such as carbon fiber cloths, a carbon fiber paper, or etc. is used for the gas diffusion layer. By making polytetrafluoethylene (PTFE) permeate into the carbon-based material, the water repellency is added to the characteristics of the gas diffusion layer. Furthermore, by the process of coating a carbon compound (or paste) which is mixed and kneaded with PTFE and carbon powder such as carbon black, the gas diffusion layer is produced. For example, such an electrode in an electrochemical fuel cell is proposed in Japanese Laid-Open Patent Application No. 5-283082.
In the conventional electrode for an electrochemical fuel cell such as the above-mentioned electrode, a carbon-based material such as carbon fiber cloths or a carbon fiber paper is used in order to improve the electric conductivity of the electrode. However, such a conventional electrode is problematic, because the cost of the electrode is high, since such a carbon-based material is expensive.